Classifications

• • H—ELECTRICITY
  • H03—ELECTRONIC CIRCUITRY
  • H03G—CONTROL OF AMPLIFICATION
  • H03G11/00—Limiting amplitude; Limiting rate of change of amplitude ; Clipping in general
• • H—ELECTRICITY
  • H03—ELECTRONIC CIRCUITRY
  • H03F—AMPLIFIERS
  • H03F1/00—Details of amplifiers with only discharge tubes, only semiconductor devices or only unspecified devices as amplifying elements
  • H03F1/52—Circuit arrangements for protecting such amplifiers
• • H—ELECTRICITY
  • H03—ELECTRONIC CIRCUITRY
  • H03F—AMPLIFIERS
  • H03F1/00—Details of amplifiers with only discharge tubes, only semiconductor devices or only unspecified devices as amplifying elements
  • H03F1/26—Modifications of amplifiers to reduce influence of noise generated by amplifying elements
• • H—ELECTRICITY
  • H03—ELECTRONIC CIRCUITRY
  • H03F—AMPLIFIERS
  • H03F1/00—Details of amplifiers with only discharge tubes, only semiconductor devices or only unspecified devices as amplifying elements
  • H03F1/52—Circuit arrangements for protecting such amplifiers
  • H03F1/523—Circuit arrangements for protecting such amplifiers for amplifiers using field-effect devices
• • H—ELECTRICITY
  • H03—ELECTRONIC CIRCUITRY
  • H03F—AMPLIFIERS
  • H03F3/00—Amplifiers with only discharge tubes or only semiconductor devices as amplifying elements
  • H03F3/189—High-frequency amplifiers, e.g. radio frequency amplifiers
  • H03F3/19—High-frequency amplifiers, e.g. radio frequency amplifiers with semiconductor devices only
  • H03F3/195—High-frequency amplifiers, e.g. radio frequency amplifiers with semiconductor devices only in integrated circuits
• • H—ELECTRICITY
  • H03—ELECTRONIC CIRCUITRY
  • H03G—CONTROL OF AMPLIFICATION
  • H03G11/00—Limiting amplitude; Limiting rate of change of amplitude ; Clipping in general
  • H03G11/02—Limiting amplitude; Limiting rate of change of amplitude ; Clipping in general by means of diodes
• • H—ELECTRICITY
  • H03—ELECTRONIC CIRCUITRY
  • H03G—CONTROL OF AMPLIFICATION
  • H03G11/00—Limiting amplitude; Limiting rate of change of amplitude ; Clipping in general
  • H03G11/04—Limiting level dependent on strength of signal; Limiting level dependent on strength of carrier on which signal is modulated
• • H—ELECTRICITY
  • H03—ELECTRONIC CIRCUITRY
  • H03G—CONTROL OF AMPLIFICATION
  • H03G7/00—Volume compression or expansion in amplifiers
  • H03G7/06—Volume compression or expansion in amplifiers having semiconductor devices
  • H03G7/08—Volume compression or expansion in amplifiers having semiconductor devices incorporating negative feedback
• • H—ELECTRICITY
  • H03—ELECTRONIC CIRCUITRY
  • H03F—AMPLIFIERS
  • H03F2200/00—Indexing scheme relating to amplifiers
  • H03F2200/294—Indexing scheme relating to amplifiers the amplifier being a low noise amplifier [LNA]
• • H—ELECTRICITY
  • H03—ELECTRONIC CIRCUITRY
  • H03F—AMPLIFIERS
  • H03F2200/00—Indexing scheme relating to amplifiers
  • H03F2200/372—Noise reduction and elimination in amplifier

Definitions

• the present invention is related to an active limiting system capable of protecting an amplifier (especially a low noise amplifier) from high input power levels.
• Low noise amplifiers are electronic amplifiers that amplify the power level of low power signals. While the low noise amplifiers amplify the power level of the signal, they keep the noise level of the output signal as low as possible. In order to perform such amplification, low noise amplifiers usually comprise at least one transistor (such as HEMT).
• Low noise amplifiers are generally used in radio communications systems. Since radio communication usually deals with low power signals (especially at the receiving end) low noise amplifiers used for the amplifying the power level of said low power signals. In the low noise amplifiers, in order to reduce the noise, sensitive components are used. Although said sensitive components are effective for reducing the noise level, they are generally vulnerable to the high power inputs. Although in the ideal cases, no high power signal is sent to the low noise amplifiers, it is possible that low noise amplifiers may be exposed to high power signals. For example in the radar applications, transmitted power may be reflected from antenna and low noise amplifier can be exposed to reflected high power through circulator. In another example, an electromagnetic bomb may generate high power signals to destroy the low noise amplifier.
• passive limiting circuits An exemplary embodiment of said passive limiting circuits is disclosed in the paper Jim Looney et al. “An Examination of Recovery Time of an Integrated Limiter/LNA” .
• Said passive limiting circuits comprise protecting elements that limit the voltage level of the input of the low noise amplifiers. Although said passive limiting l systems limit the input power, they cause high noise levels. Therefore, when low noise is needed, said passive limiting systems are not preferred.
• an active limiting system that is suitable to protect a low noise amplifier against the high power signals received from a signal input.
• Said active limiting system comprises, at least one first switch, source of which is connected to a gate voltage; at least first resistor which is connected between the gate and source of the first switch; at least one second resistor, which is connected between a drain voltage and drain of the first switch; at least one second switch, source of which is connected to said drain voltage and drain of which is connected to a signal input; at least one third resistor which is connected between the drain of the first switch and gate of the second switch;; at least one first filtering element, which blocks DC currents/voltages and which is connected between the source of the second switch and ground.
• first switch and second switch when a low power voltage signal is received from the signal input, said signal is directly sent to the low noise amplifier.
• a high power voltage signal when a high power voltage signal is received from the signal input, said high power reflected back. Therefore, low noise amplifier is protected from the high power signals.
• An object of the invention is to provide an active limiting system suitable protecting an amplifier from high input power levels.
• the other object of the invention is to provide an active limiting system that is able to be produced with low noise amplifier on a single substrate.
• Figure 1 is an exemplary circuit diagram of the active limiting system of the present application.
• Figure 2 is another exemplary circuit diagram of the active limiting system of the present application.
• Figure 3 is another exemplary circuit diagram of the active limiting system of the present application.
• LNA Low noise amplifier
• Vb Bias voltage
• Low noise amplifiers amplify the power level of the low power signals with low noise levels.
• sensitive components are used in the low noise amplifiers. Because of said sensitive components, low noise amplifiers are vulnerable against the high power inputs. Therefore, in the present application, an active limiting system that protects low noise amplifiers against the high power inputs is developed.
• the active limiting system of the present invention comprises at least one first switch (T1 ), which is preferably in the form of HEMT, having at least one source (s), at least one gate (g) and at least one drain (d), and source (s) of which is connected to a gate voltage (Vg), wherein electrical connection between the source (s) and drain (d) of the first switch (T1 ) is controlled by the gate (g) to source (s) voltage of the first switch (T1 ); at least first resistor (R1 ) which is connected between the gate (g) and source (s) of the first switch (T1 ); at least one second resistor (R2), which is connected between a drain voltage (Vd) and drain (d) of the first switch (T1 ); at least one second switch (T2), which is preferably in the form of HEMT, having at least one source (s), at least one gate (g) and at least one drain (d), source (s) of which is
• a low noise amplifier is fed by a signal received from the signal input (Ri).
• gate (g) of the first switch (T1 ) is connected to an amplifier transistor (Ta) of a low noise amplifier (LNA), through a first matching network (M1 ).
• Said low noise amplifier (LNA) may further comprises a drain voltage (Vd) and a gate voltage (Vg), a second matching network (M2), a second filtering element (b2) (such as a capacitor), which blocks DC currents/voltages and a signal output (Ro), wherein signal received from the signal input (Ri) is amplified by the amplifier transistor (Ta) and outputted from the signal output (Ro).
• first switch (T1 ) This causes first switch (T1 ) to become off state.
• second switch (T2) becomes in on state and entrance impedance of the low noise amplifier (LNA) becomes disturbed. Accordingly, high power is reflected and low noise amplifier (LNA) is protected from said high power.
• active limiting system comprises at least two second switch (T2) and at least two third resistor (R3), as shown in figure 2.
• T2 second switch
• R3 third resistor
• active limiting system comprises at least one voltage damper (a) located between the second resistor (R2) and drain (d) of the first switch (T1 ).
• Said voltage damper (a) preferably comprises at least one (preferably two) diode in order to create a voltage difference between the second resistor (R2) and drain (d) of the first switch (T1 ). Thanks to said voltage difference, when the drain voltage (Vd) becomes 0 V, any input signal is almost immediately reflected back. Therefore, high power protection of the system is improved.
• active limiting system comprises at least one third filtering element (b3) (such as a capacitor), which blocks DC currents/voltages and which is connected between the signal input (Ri) and drain (d) of the second switch (T2).
• b3 such as a capacitor
• first switch (T1 ), second switch (T2) and second resistor (R2) are connected to drain voltage (Vd) and/or gate voltage (Vg) of the low noise amplifier (LNA). Therefore, no other input is necessary for the operation of the active limiting system. Moreover, said the active limiting system and the low noise amplifier (LNA) are able to be placed on the same chip. In alternative embodiments, said the active limiting system and the low noise amplifier (LNA) may be different components (such as in the form of distinct chips).
• active limiting system comprises at least one first switch (T1 ), which is preferably in the form of HEMT, having at least one source (s), at least one gate (g) and at least one drain (d) source (s) of which is connected to a bias voltage (Vb), wherein electrical connection between the source (s) and drain (d) of the first switch (T1 ) is controlled by the gate (g) to source (s) voltage of the first switch (T1 ); at least first resistor (R1 ) which is connected between the gate (g) of the first switch (T1 ) and a gate voltage (Vg); at least one second resistor (R2), which is connected between the ground and drain (d) of the first switch (T1 ); at least one second switch (T2), which is preferably in the form of HEMT, having at least one source (s), at least one gate (g) and at least one drain (d), source (s) of which is connected to the ground and drain (Vb), wherein electrical connection between the source (s) and drain
• gate (g) of the first switch (T1 ) is suitable to be connected to an amplifier transistor (Ta) of a low noise amplifier (LNA), through a first matching network (M1 ).
• active limiting system comprises at least two second switch (T2) and at least two third resistor (R3), as shown in figure 3.
• parasitic effects of the second switches (T2) are reduced.
• first switch (T1 ) and second switch (T2) when a low power voltage signal is received from the signal input (Ri), said signal is directly sent to the low noise amplifier (LNA).
• LNA low noise amplifier

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• Engineering & Computer Science (AREA)
• Power Engineering (AREA)
• Microelectronics & Electronic Packaging (AREA)
• Amplifiers (AREA)

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• 2017
  • 2017-12-04 EP EP17934157.3A patent/EP3721554B1/en active Active
  • 2017-12-04 WO PCT/TR2017/050625 patent/WO2019112523A1/en unknown
  • 2017-12-04 CN CN201780091797.2A patent/CN110731048B/zh active Active
  • 2017-12-04 US US16/617,530 patent/US10985707B2/en active Active

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